Accounting for early death recording in acute myocardial infarction mortality indicators based on administrative data – Observational study comparing Germany and the United States

Objective To investigate whether differences in early death recording in administrative hospital data affect the comparison of acute myocardial infarction (AMI) in-hospital mortality between Germany and the United States (U.S.), and to explore approaches to account for this issue. Design Observational cross-sectional study based on administrative hospital data. The German Diagnosis-Related Group Statistics, the U.S. National Inpatient Sample and the U.S. Nationwide Emergency Department Sample were analysed. Setting Acute inpatient and emergency department (ED) care in German and U.S. acute care hospitals from 2014 to 2019. Participants Cases with treatment for AMI were identified according to the OECD indicator “AMI 30 day in-hospital (same hospital) mortality using unlinked data (admission based)”. 1.30 million acute care hospitalizations for AMI were identified in German inpatient data and 3.88 million were estimated from U.S. inpatient data. From U.S. ED data additional 25,500 patients with a first listed diagnosis of AMI, who died before inpatient admission, were estimated. Primary outcome measures National in-hospital mortality for AMI. Results While short-duration treatments due to early death are generally recorded in German inpatient data, in U.S. inpatient data those cases are partially missing. German age- and- sex standardized in-hospital mortality was substantially higher compared to the U.S. (in 2019 7.3% vs. 4.6%). The ratio of German vs. U.S. mortality was 1.6. After consideration of ED deaths in U.S. data this ratio declined to 1.4. Exclusion of same-day stay cases in German and U.S. data led to a similar ratio. Conclusions Excluding cases with short-duration treatment from the calculation of mortality indicators might be a feasible approach to account for differences in the recording of early deaths, that might be existent in other countries as well. Strengths and limitations The strength of this study is the use of large national administrative data sources. Administrative hospital data is collected for billing purposes and differences in coding, reimbursement rules, and data collection practice may impair international comparisons. The deliberate assignment of ED deaths in U.S. data to a length of stay of less than one day was done for practical reasons but might not be correct in all cases. Possible differences in coding due to different modifications of the ICD-10 should be considered, as well as the transition from ICD-9 to ICD-10 coding that took place in the U.S. in 2015. The present study focused only admission-based AMI mortality, i.e., only deaths occurring in the same hospital were captured.